To further characterize perceptual memory consolidation during sleep, we used a coarse orientation discrimination task in which participants had to discriminate the orientation of orthogonal gratings ... [more ▼]

To further characterize perceptual memory consolidation during sleep, we used a coarse orientation discrimination task in which participants had to discriminate the orientation of orthogonal gratings occluded by increasing levels of noise. In a first study (N = 11), we showed that the learning effect in this task is retinotopic (position-specific) and orientation specific. In a second experiment, we assessed the effect of nocturnal sleep, as opposed to the effect of time, on perceptual learning. A first group of participants was trained in the morning, tested in the evening and retested the next morning (morning-evening-morning, MEM, N = 11); a second group was trained in the evening, tested the next morning, and retested in the evening (evening-morning-evening; EME; N = 12). Between training and testing, EME subjects improved significantly more (after a night of sleep) than MEM subjects (after 12 waking hours). Similarly, between test and retest, performance of MEM subjects (after a full night of sleep) improved significantly more than in EME subjects (after 12 further waking hours). These results suggest a beneficial effect of sleep on coarse orientation discrimination. Further studies are needed to characterize the neural correlates of this perceptual learning and the offline consolidation of perceptual memory. [less ▲]

Context. Not only is gravitational microlensing a successful tool for discovering distant exoplanets, but it also enables characterization of the lens and source stars involved in the lensing event. <BR ... [more ▼]

Context. Not only is gravitational microlensing a successful tool for discovering distant exoplanets, but it also enables characterization of the lens and source stars involved in the lensing event. <BR /> Aims: In high-magnification events, the lens caustic may cross over the source disk, which allows determination of the angular size of the source and measurement of its limb darkening. <BR /> Methods: When such extended-source effects appear close to maximum magnification, the resulting light curve differs from the characteristic Paczyński point-source curve. The exact shape of the light curve close to the peak depends on the limb darkening of the source. Dense photometric coverage permits measurement of the respective limb-darkening coefficients. <BR /> Results: In the case of the microlensing event OGLE 2008-BLG-290, the K giant source star reached a peak magnification at about 100. Thirteen different telescopes have covered this event in eight different photometric bands. Subsequent light-curve analysis yielded measurements of linear limb-darkening coefficients of the source in six photometric bands. The best-measured coefficients lead to an estimate of the source effective temperature of about 4700[SUP]+100[/SUP][SUB]-200[/SUB] K. However, the photometric estimate from colour-magnitude diagrams favours a cooler temperature of 4200 ± 100 K. <BR /> Conclusions: Because the limb-darkening measurements, at least in the CTIO/SMARTS2 V_s- and I_s-bands, are among the most accurate obtained, the above disagreement needs to be understood. A solution is proposed, which may apply to previous events where such a discrepancy also appeared. [less ▲]

The microlensing event OGLE-2008-BLG-510 is characterized by an evident asymmetric shape of the peak, promptly detected by the Automated Robotic Terrestrial Exoplanet Microlensing Search (ARTEMiS) system ... [more ▼]

The microlensing event OGLE-2008-BLG-510 is characterized by an evident asymmetric shape of the peak, promptly detected by the Automated Robotic Terrestrial Exoplanet Microlensing Search (ARTEMiS) system in real time. The skewness of the light curve appears to be compatible both with binary-lens and binary-source models, including the possibility that the lens system consists of an M dwarf orbited by a brown dwarf. The detection of this microlensing anomaly and our analysis demonstrate that: (1) automated real-time detection of weak microlensing anomalies with immediate feedback is feasible, efficient and sensitive, (2) rather common weak features intrinsically come with ambiguities that are not easily resolved from photometric light curves, (3) a modelling approach that finds all features of parameter space rather than just the 'favourite model' is required and (4) the data quality is most crucial, where systematics can be confused with real features, in particular small higher order effects such as orbital motion signatures. It moreover becomes apparent that events with weak signatures are a silver mine for statistical studies, although not easy to exploit. Clues about the apparent paucity of both brown-dwarf companions and binary-source microlensing events might hide here. Based in part on data collected by MiNDSTEp with the Danish 1.54m telescope at the ESO La Silla Observatory. [less ▲]

We report the result of the analysis of a dramatic repeating gravitational microlensing event OGLE-2009-BLG-092/MOA-2009-BLG-137, for which the light curve is characterized by two distinct peaks with ... [more ▼]

We report the result of the analysis of a dramatic repeating gravitational microlensing event OGLE-2009-BLG-092/MOA-2009-BLG-137, for which the light curve is characterized by two distinct peaks with perturbations near both peaks. We find that the event is produced by the passage of the source trajectory over the central perturbation regions associated with the individual components of a wide-separation binary. The event is special in the sense that the second perturbation, occurring ~100 days after the first, was predicted by the real-time analysis conducted after the first peak, demonstrating that real-time modeling can be routinely done for binary and planetary events. With the data obtained from follow-up observations covering the second peak, we are able to uniquely determine the physical parameters of the lens system. We find that the event occurred on a bulge clump giant and it was produced by a binary lens composed of a K- and M-type main-sequence stars. The estimated masses of the binary components are M [SUB]1[/SUB] = 0.69 ± 0.11 M [SUB]sun[/SUB] and M [SUB]2[/SUB] = 0.36 ± 0.06 M [SUB]sun[/SUB], respectively, and they are separated in projection by r [SUB]bottom[/SUB] = 10.9 ± 1.3 AU. The measured distance to the lens is D [SUB]L[/SUB] = 5.6 ± 0.7 kpc. We also detect the orbital motion of the lens system. [less ▲]

We present results of the photometric campaign for planetary and low-luminosity object transits conducted by the OGLE survey in the 2005 season (Campaign #5). About twenty of the most promising candidates ... [more ▼]

We present results of the photometric campaign for planetary and low-luminosity object transits conducted by the OGLE survey in the 2005 season (Campaign #5). About twenty of the most promising candidates discovered in these data were subsequently verified spectroscopically with the VLT/FLAMES spectrograph. One of the candidates, OGLE-TR-211, reveals clear changes of radial velocity with a small amplitude of 82 m/s, varying in phase with photometric transit ephemeris. Further analysis confirms the planetary nature of this system. Follow-up precise photometry of OGLE-TR-211 with VLT/FORS, together with radial velocity spectroscopy, supplemented with high-resolution, high S/N VLT/UVES spectra allowed us to derive parameters of the planet and host star. OGLE-TR-211b is a hot Jupiter orbiting an F7-8 spectral type dwarf star with a period of 3.68 days. The mass of the planet is equal to 1.03±0.20 M_Jup, while its radius 1.36[SUP]+0.18[/SUP][SUB]-0.09[/SUB] R_Jup. The radius is about 20% larger than the typical radius of hot Jupiters of similar mass. OGLE-TR-211b is, then, another example of inflated hot Jupiters - a small group of seven exoplanets with large radii and unusually low densities - objects that are a challenge to the current models of exoplanets. Based on observations made with the FORS1 camera and the FLAMES/UVES spectrograph at the VLT, ESO, Chile (program 07.C-0706, 076.C-0122, and 177.C-0666) and 1.3-m Warsaw Telescope at Las Campanas Observatory, Chile. [less ▲]

Auroral ultraviolet spectra in the range from 1200 to 3200 A have been obtained by the spectrometer on board the OGO-4 satellite. Emissions of N2, H, O, and N are readily identified. Atomic and molecular ... [more ▼]

Auroral ultraviolet spectra in the range from 1200 to 3200 A have been obtained by the spectrometer on board the OGO-4 satellite. Emissions of N2, H, O, and N are readily identified. Atomic and molecular intensities are deduced from the comparison with a synthetic spectrum and compare reasonably well with some previous measurements and calculations. A feature at 2150 A is assigned to the (1-0) NO gamma band. Taking into consideration the various excitation mechanisms of NO(A2 Sigma), it is proposed that energy transfer from N2 metastable molecules to oxygen accounts for the excitation of the NO gamma bands. In particular, it is suggested that the resonant reaction between O2 and highly metastable N2 molecules may be a major source of NO(A2 Sigma). [less ▲]

Limb spectra of the OH nightglow emission corresponding to the ∆v=1 and ∆v=2 sequences have been collected with the VIRTIS infrared imaging spectrograph on board Venus Express between April 2006 and ... [more ▼]

Limb spectra of the OH nightglow emission corresponding to the ∆v=1 and ∆v=2 sequences have been collected with the VIRTIS infrared imaging spectrograph on board Venus Express between April 2006 and October 2008. A detailed statistical analysis shows that the peak intensity and altitude of the two vibrational sequences are significantly correlated, with a mean intensity ratio of the two sequences of 0.38±0.37. The altitude of the maximum of the ∆v=2 emission is located ~1 km lower than ∆v=1. A spectral analysis shows that the Δv=1 sequence is composed at 44.6% by the (1–0) band, 9.3% by the (3–2) band and 7.1% by the (4–3) band. The Δv=2 emission is best fitted if solely including the (2–0) band. A non-LTE model of OH vibrational population by the O3+H reaction including radiative and collisional relaxation has been used to compare the expected spectral distribution, the altitude of the emission peak and the emission rate under different assumptions on the quenching processes to those observed with VIRTIS. The adopted carbon dioxide, atomic oxygen and ozone densities are based on recent Venus Express remote sensing measurements. We find that the “sudden death” quenching scheme by CO2 produces inadequate spectral distribution between the various bands and insufficient airglow brightness. Instead, the observed spectral distribution and the total emission intensity are reasonably well reproduced with the single quantum jump model, a O density profile peaking at 103.5 km with a maximum value of 1.9×1011 cm−3, a O3 density profile peaking at 5.8×106 cm−3 at 96.5 km and a H density profile close to 108 cm−3 between 90 and 120 km, in agreement with several photochemical models. [less ▲]

A close reading of Pausanias’ visit of the north side of the Athenian Acropolis suggests that the present identification of the Erechtheion, which dates back to the seventeenth century, is highly doubtful ... [more ▼]

A close reading of Pausanias’ visit of the north side of the Athenian Acropolis suggests that the present identification of the Erechtheion, which dates back to the seventeenth century, is highly doubtful, as some very few scholars have concluded during the last three decades. The present analysis addresses the word "oikema" used by Pausanias in his description of the Acropolis, comparing this use with all the other places where it appears in the Periegesis. We may conclude that the asymetrical Ionic temple was completely devoted to Athena Polias. Therefore, the so-called Erechtheion has still to be found. [less ▲]

Subsidence of an chalky oil field is described. The mechanical behaviour of the chalk partly saturated by oil and water is described and allows to model the compaction occurring within a simple reservoir ... [more ▼]

Subsidence of an chalky oil field is described. The mechanical behaviour of the chalk partly saturated by oil and water is described and allows to model the compaction occurring within a simple reservoir model during the depletion as well as during the water injection. [less ▲]

A bird named Karšiptar, attested only once in the Avesta at V 2.42, was charged with the propagation of the religion in the vara. The Avestan term karšiptar, literally « black-winged », was identified as ... [more ▼]

A bird named Karšiptar, attested only once in the Avesta at V 2.42, was charged with the propagation of the religion in the vara. The Avestan term karšiptar, literally « black-winged », was identified as a crow by Gershevitch, who based his hypothesis on a mythological parallel in Armenian. It is not the only attestation of a crow fulfilling the role of messenger in Indo-Europeans legends. Cognate is the Middle-Persian name karšift. In the texts, he represents the leader of the birds and is described by two terms: cakrawāk and carg. Here can also be considered cixrāz, the name of the leader of the birds according to MX 60.9. These three terms may be etymologically related: cakrawāk < *cakra-vāka- “the one who says cakra”, with an historical spelling ; cixrāz, which shows a different suffix but is semantically identical < *cakra-vāca- ; and carg, which would be a form without a suffix and displaying a metathesis. Unfortunately, this does not permit a conclusive identification of the bird. No argument allows us to make a decisive choice, but the hypothesis of the crow combines the etymological signification with the role of messenger between the two worlds that is attributed to him. [less ▲]